Over-scanning shield provided in colored television tube between the mask support and the tube



Oct. 14, 1969 w, scH ET AL.. 3,473,065

OVER-SCANNING- HIELD PROVIDED IN COLORED TELEVISION v TUBE BETWEENTHEMASK SUPPORT AND THE TUBE Filed Jan. 18, 1966 2 Sheets-Sheet 1lflllllllllwlull Oct. 14, 1969 w w z ET AL 3,473,065 OVER-SCANNINGSHIELD PROVIDED IN COLORED TELEVISION TUBE BETWEEN THE MASK SUPPORT ANDTEE TUBE Filed Jan. 18, 1966 2 Sheets-Sheet 2 Jim-.5.

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United States Patent OVER-SCANNING SHIELD PROVIDED IN COLORED TELEVISIONTUBE BETWEEN THE MASK SUPPORT AND THE TUBE James W. Schwartz, WesternSprings, and Daniel J. McCarthy, Glen Ellyn, Ill., assignors to NationalVideo Corporation, Chicago, [1]., a corporation of Illinois Filed Jan.18, 1966, Ser. No. 521,370 Int. Cl. H013 29/46 U.S. Cl. 313-85 ClaimsABSTRACT OF THE DISCLOSURE This invention involves a novel shieldagainst overscanning in a color television tube wherein the shield isformed of a continuous conductive foil having a rolledover edge which iscarried by and compressed between the mask support structure and thetube funnel.

This invention relates to color television picture tubes, and morespecifically relates to a novel shield structure within the tube toeliminate the adverse effects of overscanning.

It is well known in the color television tube art that a shielding meansshould be disposed about the inner periphery of the tube adjacent thefront plate of the tube to intercept primary and reflected electronsfrom the side walls of the tube funnel caused by over-scanning of theelectron gun. Such electrons if not intercepted will result in spuriousexcitation of the phosphor coating of the tube face causing undesiredwhite streaks to occur in the color picture.

Shields for this purpose of thin conductive metal have been secured tothe interior of the tube and between the mask and funnel by welding.This welding, however, can result in sparks and the possible transfer ofcopper to the phosphor tube coat. The copper in the phosphor coat willthen affect the color response of the coat.

The principle of the present invention is to provide a novel shieldagainst over-scanning in a color television tube wherein the shield isformed of a continuous conductive foil having a rolled-over edge whichis carried by and compressed between the mask support structure and tubefunnel.

The shield of the present invention will be held securely in placewithout the necessity of welding and will, at the same time, be aneffective barrier and prevent overscanning electrons from affecting thepicture.

Accordingly, a primary object of this invention is to eliminate the needfor welding of an over-scanning shield to the funnel of a colortelevision tube.

Another object of this invention is to provide a novel continuous foilwhich has a rolled-over edge which is received solely by the masksupport structure of a color television tube with the foil serving as anover-scanning prevention means.

Still another object is to provide a one-piece shield which issufliciently flexible to fit tightly and securely between the mask frameand glass envelope irrespective of small dimensional changes in theframe and envelope.

These and other objects of this invention will become apparent from thefollowing description when taken in connection with the drawing, inwhich:

FIGURE 1 is an exploded perspective view of a color television tubewhich incorporates the shield of the present invention.

FIGURE 2 is a side cross-sectional view showing the glass front plate ofFIGURE 1.

FIGURE 3 is a front view of the mask assembly of FIGURE 1.

FIGURE 4 is a top view of FIGURE 3.

FIGURE 5 is a cross-sectional view of FIGURE 3 taken across the lines5-5 in FIGURE 3.

FIGURE 6- is a front view of the foil shield of the present invention.

FIGURE 7 is a cross-sectional view of FIGURE 6 taken across the lines7--7 in FIGURE 6, and illustrates the rolled edge of the foil.

FIGURE 8 is a cross-sectional view of the assembled tube incorporatingthe novel shield of the invention.

FIGURE 9 shows an enlarged cross-sectional view of the manner in whichthe shield is supported and connected to the funnel along withsupplementary contact spring means.

Referring first to FIGURE 1, there is illustrated therein a typicalcolor television tube which comprises a glass funnel 10 which may havean electrically conductive interior, and which receives internallythereof a mask support structure 11 which carries a mask 12 as anintegral part thereof.

A shield 13 which is the subject of the present invention is theninterposed between mask assembly 11 and the funnel 10, being compressedbetween the mask frame and the inner conductive surface of the funnel10.

When the device of FIGURE 1 is assembled, it will be seen that the frameassembly 11 and shield 13 are contained between the interior of thefunnel 10 and the glass face plate 14. The narrow end of the funnel willcontain suitable electron gun means and focusing means in the usualmanner.

The funnel 10 is shown in FIGURES 8 and 9, and is of the standard glassconstruction with the extending funnel walls with a carbon-containing orother suitable conductive coating shown as coating 10a in FIGURE 9. Faceplate 14 is also suitably prepared with the usual coating on theinterior thereof, and is provided with a plurality of support buttons20, 21 and 22 which carry the mask support structure 11, as shown inFIGURE 2.

The mask support structure 11 is best shown in FIG- URES 3, 4 and 5 andis comprised of a generally L- shaped cross-section annular metal member30 which defines a rectangular opening 31 in the rear thereof. Asuitable mask 12 is then directly secured over the outer periphery ofthe support member 30 as shown. The support member 30 is then providedwith a plurality of spring members shown as elements 35, 36 and 37 onthe sides thereof which have outwardly extending end portions and whichare each suitably connected to the support 30 as by riveting or welding.Springs 35, 36 and 37 of FIG- URES l, 3 and 4 connect to support buttons20, 21 and 22 of FIGURE 2 in a snap-in type arrangement to secure themask 12 and mask support frame 11. in position with respect to faceplate 14 in the usual manner.

The novel shield of the present invention is best shown in FIGURES 6 and7 and is shown in position with respect to the assembled components inFIGURES 8 and 9.

Thus, in FIGURES 6 and 7, the shield 13 is constructed of a generallyannular metallic foil which may be of aluminum having a thickness whichmay be of the order of 5 mils.

The shield 13 has a re-entrantly bent outer periphery 40 which extendsfrom a central web 41. A rectangularshaped opening 42 then defines theend of web 41. The web 41 serves as the shielding portion of the shieldstructure and extends around the outer periphery of the mask 12, inorder to effect the desired shielding action. It will be noted thatsince the web 41 is of a thin foil it can be compressed into shapeduring the assembly of the tube and maintains itself in a secureposition during heating and compression operations of the assembly step.

As further shown in FIGURE 9, the mask frame 11 may also have secured toit a spring 26 which passes through an opening in the foil shield andmakes further contact with the conductive interior surface of thefunnel.

Although this invention has been described with respect to its preferredembodiment, it should be understood that many variations andmodifications thereof will now be obvious to those skilled in the art,and it is preferred, therefore, that the scope of the invention belimited not by the specific disclosure hereof, but only by the appendedclaims.

The embodiments of the invention in which an exclu- ;sive privilege orproperty is claimed are defined as follows:

1. A shield for shielding against over-scanning in a color televisiontube; said color television tube comprising a glass funnel, a glass faceplate having a generally dished shape connected to said funnel about thelargest outer periphery of said funnel, and a mask and frame assemblysupported within said dished shape glass face plate; said shieldcomprising a continuous deformable thin conductive foil having anenlarged opening therethrough to permit passage of an electron beamthrough the major area of said mask; said shield having a web portionextending from said opening to the outer periphery thereof; said outerperiphery of said shield being interposed between adjacent annularsurface portions of the mask support frame and the interior of saidfunnel and being secured therebetween by pressure contact with saidadjacent annular surface portions.

2. The device as set forth in claim 1 wherein said outer periphery ofsaid shield comprises a re-entrantly folded section extendingsubstantially at right angles to said web portion.

3. The device of claim 1 wherein said shield outer periphery comprises arim portion bent substantially perpendicular to said web portion; saidweb portion having a substantially constant radial length ofapproximately 1 inch.

4. The device of claim 1 wherein said shield is constructed of metallicfoil having a thickness of approximately 5 mils.

5. The device of claim 4 wherein said rim portion comprises a doublethickness section of said foil defined by a re-entrant bend of said foilat the outer periphery thereof.

References Cited UNITED STATES PATENTS 2,806,162 9/1957 McQuillen et al313-85 X 2,806,165 9/1957 Law 313-92 X 2,890,377 6/1959 Fyler 313-92 X2,897,392 7/1959 Fiore 313-92 2,906,904 9/1959 Woughter et al. 313-853,313,975 4/1967 Oess 313-68 X 3,346,753 10/1967 Haas 313-85 X JAMES W.LAWRENCE, Primary Examiner V. LAFRANCHI, Assistant Examiner US. Cl. X.R.313-313

